Effect of aging treatment on microstructure, mechanical properties and corrosion resistance of 2219 aluminium alloy laser welded joint

As a common heat-treatable aluminium alloys, AA2219 welded components are often applied in aerospace and rail transportation fields. However, the service performance like mechanical properties and corrosion resistance of this alloy are difficult to achieve a synergistic improvement after heat treatment. In this paper, different artificial aging processes were treated to establish the relationships between the microstructure, mechanical properties and corrosion resistance of the welded joints. The hardness of the joints increased first and then decreased with the increase of aging time. The tensile strength of aging treated joint increased by 46.4 % compared with the as-welded condition due to the dispersed distribution of fine precipitates. Meanwhile, the decreased potential difference between the Al–Cu precipitates, matrix, and precipitate-free zone enhances the corrosion resistance of the welded joint. Aging at 175 °C for 12 h produced the highest charge-transfer resistance (27564 ± 2776 Ω cm 2 ), a 59.2 % increase over the as-welded condition (17310 ± 609 Ω cm 2 ), indicating superior corrosion resistance of the welded joint. The corresponding research results have laid a foundation for the long-term service of aluminium alloy welded structures.